Ice detector means



June19, 1951 w. B. POND ICE DETECTOR MEANS Original Filed Aug. 11, 1943 I I mmvrdn WilbhmBPozzd HTTORNEY Patented June 19, 1951 ICE DETECTOR MEANS William B. Pond, Pomona, Calif., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Original application August 11, 1943, Serial No. 498,247. Divided and this application January 10, 1949, Serial No. 70,067

3 Claims.

The present application is a division of copending application Serial No. 498,247, filed August 11, 1943 and now U. S. Patent No. 2,476,217, granted July 12, 1949 and assigned to Bendix Aviation Corporation, and relates to control devices and more particularly to means responsive to icing conditions prevailing on an exposed aircraft surface for operating inflatable ice eliminating units for aircraft or suitable indicator means.

It has been observed that such units or boots give better ice removal if approximately an eighth of an inch of ice is allowed to accumulate before the boots are inflated. This is because the ice must build to a definite thickness in order to develop enough tensile strength to overcome adhesion. If the inflatable ice eliminating boots are operated with insuflicient ice accumulated on them, the stretch of the rubber cracks the thin layer of ice, breaking it into many very small pieces, some of which are dislodged, but most of which remain. Further accumulation of ice builds on the little particles which remain and thus develops a flexible ice which is really composed of a number of separate little islands. Once such a condition has been established, additional cycles of inflation and deflation are relatively ineffective because further ice formation tends to accumulate only on the remaining particles and the stretch of the rubber naturally localizes in the areas between the islands without disturbing them. However, if the ice be permitted to accumulate to a greater thickness, it becomes increasingly more dificult to apply suflicient pressure through the boots to effect the cracking of the ice to facilitate its removal.

It is therefore of extreme importance that the operator of the plane be so advised or that the inflatable ice eliminating boots be operated when the ice has accumulated to the optimum thickness for its removal.

An object of my invention therefore is to provide control means responsive upon such predetermined optimum icing conditions prevailing on an aircraft surface to operate suitable ice eliminating means for removing the accumulated ice from such surface, whereby said control means is simultaneously conditioned for re-operation upon a recurrence of such optimum predetermined condition.

Another object of my invention is to provide electronic control means directly responsive to the thickness of an ice accumulation for performing a control function.

Another object of my invention is to provide 2 means mounted directly upon a boot responsive to an ice accumulation thereon for initiatingv the operation of the boot.

Another object of my invention is to provide a novel resistance leak element mounted upon an inflatable ice eliminating boot and responsive to the formation of a predetermined thickness of ice upon the boot so as to control'an electronic circuit for initiating the operation of the boot, whereupon the ice accumulation will be removed and the resistance leak element reconditioned for response to a recurrent formation of a predetermined thickness of ice upon the boot.

Another object of my invention is to provide control means responsive to ice thickness and means for removing the ice from the control means operated by the said ice thickness responsive means. 1

A further object of my invention is to provide a compact control device responsive to ice thickness of great efiiciency in comparison to its size and of such simplicity in construction as to adapt it for manufacture and installation at low cost.

Other objects and advantages of this invention are set forth in the following description, taken with the accompanying drawings; and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only and we may make changes in detail, especially in matters of shape, size and arrangementof parts within the principle of the invention to the full extent indicated by the broad and general meanings of the terms in which the appended claims are expressed.

In the accompanying drawings which form a part of this specification like characters of reference indicate like parts in the several views therein.

Figure 1 is a cross sectional view of a portion of the forward edge of a wing of a plane illustrating the application of one form of my control device.

Figure 2 is an enlarged section view of Figure 1 taken along the lines 'l-'l and looking in the direction of the arrows.

Figure 3 is a diagrammatic view illustrating a form of control circuit which may be utilized with my control device of Figure 1.

In the form of my invention illustrated in Figures 1 through 3, there is indicated by numeral IIB an airplane wing provided with an inflatable ice eliminating boot Ill formed of resilient rubber like material and positioned along the leading edge of the wing [H].

The boot ill maybe of the type shown for example in the copending application of Donald M. Lawrence, David Gregg and Myron L. Taylor, Serial No. 498,248, filed August 11, 1943 now Patent No. 2,515,519 issued July 18, 1950 and owned by the assignee of the present application and has provided inflatable tubes I I2 and I I3.

The tubes H2 and H3 are expanded and contracted in a recurring cycle of operation at intervals which may be determined by a timing arrangement such as shown in the copending application of Myron L. Taylor, William B. Pond and Herbert A. Eayrs, Serial No. 498,250, filed August 11, 1943 and now U. S. Patent No. 2,444,208, granted June 29, 1948 and assigned to Bendix Aviation Corporation.

In the form of the invention illustrated in Figures 1-3 there is shown a control device 99 which comprises a sleeve I screw threaded at the opposite ends and formed of suitable electrically conducting material. The sleeve I00 has provided a projecting annular flange IOI positioned intermediate the opposite ends thereof. A second flange I02 likewise formed of electrically conducting material is screw threadedly engaged at one end of the sleeve I00 in spaced relation to the flange IOI. concentrically mounted Within the sleeve I00 is an insulation member I03 formed of a suitable moisture repellant material such as porcelain or other ceramic material suitably treated in a manner well known in the art so as to retard wetting of the surface of the insulation member I03 and thereby maintain high surface resistivity.

The insulation member I03 may be fastened Within the sleeve I00 by means of any suitable a material and has provided a portion I04 which projects from the outer end of the sleeve I00 through the flange I02. The outer end of the insulation member I03 has mounted thereon a pointed cap-like member I05 which is fastened thereto in any suitable manner. The member I05 is formed of suitable electrically conducting material and is spaced apart from the flange I02 and the sleeve I00 by the insulation member I03. A longitudinally extending channel I05 is concentrically formed in the insulation member I03 and extends from one end thereof to the opposite end.

An electrical conductor I01 is fastened at one end by silver solder or other suitable means to r the cap-like member I05. The conductor I0! extends from the cap I05 longitudinally through the channel I06. A second conductor I08 is connected to the sleeve I00 by a nut I03 adapted to be screw threadedly engaged on the sleeve I00. As shown in Figure 1 the control device is arranged to be secured at one end in a suitable aperture formed in the leading edge of an aircraft wing IIO by the fastening nut I09. The flange portion IOI is adapted to engage the outer surface of the wing H0 while the nut I09 engages the opposite inner surface thereof so as to fasten securely the control device thereto.

The sleeve I00 projects through a suitable aperture formed in the inflatable ice eliminating boot III so that the flange I02 engages the outer surface of the boot III and is fastened in place by screw threadedly engaging the sleeve I00. Thus the boot III is positioned between the flanges IOI and I02 carried by the sleeve I00. The sleeve I00 as shown in Figure 1, further extends between the inflatable tubes II2 and IE3 previously described. -As shown in Figure 3, the flange I02 and cap I05 spaced apartby the insulator I03 are connected to a suitable control circuit through the electric conductors I01 and I08.

The said control circuit as illustrated in Figure 3, has provided an electronic valve H4 having provided a cathode I I5, anode or plate II5, a shield grid II'I', a control grid IIS, and a heater or filament I I9.

The shield grid II! is connected by a conductor I to the positive terminal of a suitable source of electrical energy I2I. The negative terminal of the source of electrical energy I2I is connected by a conductor I22 to the positive terminal of the source of electrical energy I 23. The negative terminal of the source of electrical energy I23 is connected by a conductor I24 to one terminal of a grid resistance I25. The opposite terminal of the grid resistance I25 is connected by a conductor I28 to the control grid H8. The cathode H5 is connected by a conductor I21 to the conductor I22 leading from the negative terminal of the source of electrical energy I2I to the positive terminal of the source of electrical energy I23. I

The filament Il9'is connected at one terminal to the conductor I2! leading to the negative terminal of the source of electrical energy I2I while the opposite terminal of the filament H9 is connected to one terminal of a filament resistance I28. The opposite terminal of the resistance I28 is connected to the conductor I20 leading to the positive terminal of the source of electrical energy I2I.

The anode or plate H6 is connected by a conductor I29 to one terminal of an electromagnetic coil I30. The opposite terminal of the coil I30 is connected by a conductor I3I to the conductor I20, leading to the positive terminal of the source of electrical energy I2I.

The electromagnetic coil I30 is so arranged that upon suflicient energization thereof, spring tensioned switch arms I32 and I32A will be actuated so as to close switch contacts I33 and I33A, respectively, The switch arms I32 and I32A are normally biased by spring tension so as to open the contact I33 and I33A, respectively, upon insufficient energization of the electromagnet I30.

An electrical conductor I34 connects the switch arm I32 preferably into a timer circuit of the type shown in the copending application of Myron L. Taylor, William B. Pond, and Herbert A. Eayrs, Serial No. 498,250, filed August 11, 1943 and now U. S. Patent No. 2,444,208, granted June 29, 19 8 and assigned to Bendix Aviation Corporation, and indicated generally in Figure 3 by the numeral I35 while the switch contact I33 is also connected into the circuit by a conductor I36. As described in the latter application, the switch arm I32 may be arranged for closing a circuit for initiating a cycle of operation.

Similarly the switch arm I32A is arranged to control a circuit for operating a suitable indicator I35A such-as a light, alarm or whistle.

It will be further noted that the cap I05 of the control device 99 is connected by the conductor III! to the conductor I20 leading through the grid resistance I25 to the negative terminal of the source of electrical energy I23 while the flange I02 is electrically connected by the conductor I08 to the conductor I21 leading to the positive terminal of the aforesaid source of electrical energy I23.

As shown in Figure 2, the cap I05 and the flange I02 are spaced apart by the insulation member I03. However, upon ice being accumulated on the boot of sufficient thickness as to contact both the flange I 02 and the cap-I05 an'electrical leakage path will be closedbetween the'elements I02 and I05 through the ice constituting a resistance leak as shownin Figure 1., The conductivity of ice is set forth in a publication by N: Ernest Dorsey entitled: Properties of: Ordinary Water Substances, on pages. 505-510v of that publication. Itwill be readily seen. from Figure 3 that the closing: of an electrical path between the flange I02 and the cap I05 will constitute a grid resistance leak that will eiTect a decrease in the negative potential of the control grid IIB so as to cause an increase in the electronic flow within the electronic valve I I4 to the plate I I6 causing a corresponding increase in the flow of current in the plate circuit. The electromagnetic coil I30 is so arranged that upon such increase in the electronic flow in the plate circuit the electromagnetic I30 will be sufiiciently energized so as to cause the actuation of the switch arm I32 into engaging relation with the contact I33. However, upon the electrical path between the cap I05 and the flange I02 being opened, there will be effected an increase in the negative potential of the control grid II8 so as to decrease the electronic flow within the electronic valve H4 to the plate H6. This decrease in the electronic flow will cause a corresponding decrease in the flow of current in the plate circuit so that the electromagnetic coil I30 will be insufliciently energized for holding the switch arms I32 and I32A so as to close contacts I33 and I33A whereupon the spring tensioned switch arms I32 and I32A will be biased into a contact opening relationship with the contacts I33 and I33A, respectively.

In the operation of my novel control device 99 upon an ice accumulation on the boot of a predetermined thickness suflicient to close an electrical path between the cap I05 and the flange I02 the electromagnet I30 will actuate the arms I32 and I32A, so as to close the contacts I33 and I33A, so as to energize the indicator I35A and cause the initiation of a cycle of operation such as explained in the U. S. Patent No. 2,444,208, whereupon the tube II3 will be inflated causing the expansion of the boot III at the side of the sleeve I adjacent the tube II3. After a time interval determined by the timer I 35, the boot I II will be deflated as explained in the aforesaid patent. Then the tube II2 will be inflated and in turn deflated expanding and contracting the boot II I, at that side of the control device 00 adjacent the boot H2.-

Such inflation and deflation of the boot III as will be readily apparent, will cause the cracking of the ice formed thereon and adjacent the control device 99 which ice will in turn be carried away by the airflow.

The remaining boots of the plane will be inflated and deflated as explained in the U. S. Patent No. 2,444,208 until the cycle of operation is completed, whereupon operation of the inflatable ice eliminating system will cease until initiated again by the formation of an ice accumulation of sufficient thickness to close an electrical path from the cap I to the flange I02 causing the closing of the switch contact I33 whereupon the cycle of operation of the system will be repeated.

While in the illustrations herein I have shown my control device as controlling a timer of a type disclosed in the U. S. Patent No. 2,444,208, it will be readily apparent that if desired, the same may control any suitable type of electronic control or may control an indicator and the inflatable 6 ice eliminating system may becontrolled manually by the pilot.

Thus; although only one embodiment of. my invention has been illustrated and described, various changes in. the form and relative arrangementof the parts, which will now appear to those skilledin the art, may be made without departing from the scope of the invention. Reference is therefore to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

l. The combination, including a control device mounted on the wing of an airplane for indieating an accumulation of ice having a predetermined thickness, said control device including a sleeve, a flange projecting from said sleeve, an insulation member positioned in said sleeve and having one end thereof projecting from one end of said sleeve, and a cap mounted on said insulation member and positioned in spaced relation to said flange; an electrical control circuit, said flange and said cap of said control device connected in said electrical control circuit, an expansible member mounted on a surface of the wing of said airplane for removing an accumulation of ice from said surface, said flange and said cap projecting from the exterior surface of said expansible member and directly responsive to an accumulation of a redetermined thickness of ice on said member for increasing electrical leakage through said control circuit, and means controlled by said leakage circuit for initiating operation of said expansible member.

2. A device of the character described, comprising, in combination, a mechanism including an expansible boot carried by an aircraft for the removal of ice accumulations on said aircraft, means for operating said expansible boot, control means for initiating operation of said boot, means operatively connecting said control means to the boot operating means, said control means projecting through said boot and from the exterior surface of said boot and responsive to an accumulation on the exterior surface of said boot of a predetermined thickness of ice to cause said operating means to effect expansion of said boot, whereby upon expansion of said boot removal of said ice is effected by said boot and said control means is reconditioned for initiating operation of said boot upon succeeding accumulation of ice upon the exterior surface of said boot.

3. A device of the character described, comprising, in combination, a mechanism including an expansible member carried by an aircraft for the removal of ice accumulations on said aircraft, means for operating said expansible member, an electrical control circuit for said operating means, a first electrode aflixed to said expansible member, a second electrode projecting from said expansible member in spaced relation to said first electrode and insulated therefrom, an electronic valve having a plate and cathode connected in said control circuit and a control grid, a source of electrical energy, means connecting the source of electrial energy between the cathode and grid, said connecting means including a resistor element between the source and grid, said source of electrical energy normally applying a control bias to said grid to prevent said control circuit from effecting operation of said expansible member, one of said electrodes connected to the cathode and the other of said electrodes connected to the grid of said electronic valve to provide an electronic leakage path from the grid to the source of electrical energy, said WILLIAM B. POND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,071,148 Weisberg et al Feb. 16, 1937 2,358,406 Lichtgarn Sept. 19, 1944 2,373,255 McGoldrick Apr. 10, 1945 

